Sea wall structures, sea walls and methods of manufacture and assembly of the same

ABSTRACT

A sea wall structure ( 10 ) comprising a rigid supporting structure ( 12 ) and one or more hollow tanks ( 14 ) affixed to the supporting structure ( 12 ), wherein the volume of the tank or tanks ( 14 ) is such that, when filled with air, their displacement is sufficient to support the weight of the sea wall structure ( 10 ) and thus enable the sea wall structure to be floated on water ( 300 ). The rigid supporting structure ( 12 ) is suitably made from cast, reinforced concrete, and the tank or tanks ( 14 ) are suitably blow-moulded plastics components having peripheral edges that are moulded into the concrete. The sea wall structure ( 10 ) is ideally modular, having side edges that are adapted ( 28, 30 ) to engage with adjacent structures ( 10 ) to form a wall, caisson or the like.

This invention relates to sea wall structures, sea walls and methods of manufacture and assembly of the same, respectively.

Sea walls are used in a wide range of marine or civil engineering applications to separate two or more bodies of water (for example, as a harbour wall), or as a retaining structure (such as a dyke), to hold-back a body of water.

Sea walls are traditionally constructed from locally-sourced construction material, such as sand or gravel found on the sea bed in the immediate vicinity of the intended sea wall, which is piled up, using dredgers, to a level above the waterline. To prevent the construction material from washing away, one or more layers of retaining material, such as geotextiles, rocks and boulders, concrete etc. are then placed or poured over the construction material to cap it and hence keep it in-situ. The use of dredgers is increasingly becoming disapproved of because of the adverse effects that they cause to marine ecosystems by disturbing and/or redistributing the sea bed. Further, marine life living in the sea bed, are often unable to survive the dredging process, or to survive in the new structure, resulting in death and subsequent decomposition within the sea wall's fill material, which can have adverse effects later on, for example, outgassing of methane, or forming voids in the granular fill material. In addition to the foregoing drawbacks, dredging is a slow, labour- and energy-intensive procedure, and tends to be expensive.

In attempts to combat one or more of the aforesaid problems, many modern sea walls are constructed from concrete slabs, which are placed vertically on the sea bed, and which interlock to form a contiguous structure. However, to be effective, this solution requires a large amount of concrete and due to the poor environment credentials of concrete as a building material, as well as the need to manufacture the slabs in the “dry” before transporting them to site (the over-land and over-sea transportation cost; and fuel/energy usage of which tending to be relatively high), concrete sea walls are also considered by many to be undesirable.

Nevertheless, a significant need for sea walls exists, for example in large-scale civil engineering projects such as tidal power generation barrages, coastal erosion and flood defences and so forth.

It will therefore be clear from the foregoing that a need exists for a solution to one or more of the above problems and/or an alternative to existing sea walls and construction techniques for them.

Various aspects of the invention are set forth in the appended claims.

According to an aspect of the invention, there is provided a sea wall structure comprising a rigid supporting structure and one or more hollow tanks affixed to or within the supporting structure.

Another aspect of the invention provides a sea wall formed from a plurality of sealingly interconnected sea wall structures as herein described.

Another aspect of the invention provides a method of manufacturing a sea wall structure as herein described.

Another aspect of the invention provides a method of assembling a sea wall from a plurality of sea wall structures as herein described.

By providing a sea wall structure comprising a supporting structure and one or more hollow tanks, it is possible to vastly reduce the amount of material required to construct the sea wall structure as the portion of it formed by the tank or tanks is essentially hollow.

Further, the tank or tanks can be useful in transporting the sea wall structure over land because when empty (i.e. filled with air), this renders the sea wall structure considerably lighter and thus more easily and inexpensively handled (lifted/moved) compared to, say, a solid concrete wall structure.

Further, the tank or tanks can be useful in transporting the sea wall structure over water because, in certain embodiments, the size of the tank or tanks can be designed in such a way that their displacement in water is sufficient to support the weight of the sea wall structure when floated on water. This means that the sea wall structure can be floated and towed to site, rather than having to be loaded onto a barge or the like, which greatly simplifies the installation and assembly of a sea wall constructed from one or more of the sea wall structures.

Moreover, the tank or tanks can be filled with ballast, such as sea water, to orient and/or to sink the sea wall structure and also to render it more heavy and/or solid.

Put another way, the tank or tanks of the invention can serve as buoyancy or ballast tanks, depending on whether they are empty (or filled with a gas), or full (e.g., filled with water or other ballast), respectively.

The supporting framework is suitably manufactured from concrete, such as moulded, poured, reinforced concrete. Concrete is readily available in most parts of the world, and thus it is possible, in certain situations, to manufacture the sea wall structure locally (i.e. close to the final installation site) by the use of moulds and the like. This, advantageously, reduces the environmental impact of transporting the sea wall structure. The invention also reduces the amount of concrete that is used in the manufacture of sea walls, compared with solid concrete wall structures.

The tank or tanks are suitably formed from blow-moulded plastics, and are preferably manufactured from locally-sourced recycled materials, thereby reducing the structure's environmental impact yet further. The tank or tanks are ideally designed with formations, such as flanges comprising through holes, that “key” with poured concrete of the supporting framework.

Additionally or alternatively, and in the situation where the supporting structure of the sea wall structure is manufactured from poured, reinforced concrete; the or each tank may comprise one or more engagement means adapted in use, to engage with the rebar of the reinforced concrete supporting framework prior to pouring of the concrete. The provision of engagement means usefully enables the or each tank to be clipped to, or otherwise temporarily connected to the rebar, thereby facilitating retaining the or each tank in its correct position during the concrete pouring and setting procedure (otherwise, the tanks might float out of the concrete before it sets). The engagement means, where provided, may also help to anchor the tanks into the concrete, thereby improving the integrity of the sea wall structure.

Where the supporting structure of the sea wall structure is made from poured concrete, this may usefully form a seal with the tanks that are in contact with the concrete, thereby preventing water from leaking through the sea wall structure (via gaps between the supporting structure and the tanks), in use. It may be necessary, in certain situations, to apply a bonding or sealing agent (such as an adhesive layer, bitumen etc.) to the tank or tanks prior to pouring the concrete, especially where the adhesion of the concrete to the chosen material of the tanks is poor, or likely to be.

Each sea wall structure is preferably generally cuboidal, to facilitate the modular assembly of a sea wall by placing several like sea wall structures side-by-side. In a preferred embodiment of the invention, the sea wall structure has “left” and “right” sides, which are complementarily engageable with one another. In one possible embodiment, the left and right sides of the sea wall structure comprise lips that partially overlap one another when two sea wall structures are placed side by side. Such a configuration, when correctly implemented, may provide a small channel (formed by two L-shaped lips coming together) into which a seal can be inserted or poured, for form a watertight (or a substantially watertight) seal between the edges of adjacent sea wall structures.

In a preferred embodiment of the invention, the (vertical) side edges of the sea wall structure comprise complementary connectors to engage adjacent sea wall structures with one another. In one embodiment of the invention, the connectors comprise a cup and pin arrangement: the cups and pins being disposed on opposite sides of each sea wall structure so that they can engage to lock two adjacent sea wall structures together. Preferably, the connectors are self-centring, for example, with the pin having a tapered point that engages a part-conical portion of the cup. Thus, as the pin is lowered into the cup, it self-aligns. More preferably still, either or both of the complementary connectors are slightly canted such that when they are engaged with one another, at least one of the two connected sea wall structures is “pulled into” engagement with the other. Finally, a tubular steel pile can be installed within the sleeves formed by the connection and the top of this steel pile can be bolted to connection points on the top of the sea wall structure.

In certain embodiments of the invention, each tank may be provided with a valve. The valves are suitably controllable remotely to enable each tank to be filled individually, in groups, or together. This is suitably accomplished by providing electronically-controllable valves. The outlet of each valve, where provided, communicates with the interior of a tank, and the inlet of each valve, where provided, is connected to a fluid source. The fluid source may be sea water in or upon which the sea wall structure is located. Alternatively, the fluid source may comprise pipework connected to an air or gas supply; and/or to a supply of liquid (e.g. water) or other flowable (fluid-like) ballast (e.g. fine, dry sand, glass beads, metal powder and the like).

An advantage of being able to flood and empty each tank as desired is apparent in a possible assembly methodology for a sea wall constructed from the sea wall structures of the invention. Specifically, the sea wall structure can be floated to site by emptying all of its tanks so that it floats in water. When manoeuvred into position, the lowermost tanks can be flooded with water to sink the lower end of the sea wall structure, thereby beginning to right it in the water (stand upright). Then, further tanks can be flooded with sea water to continue the righting procedure until the sea wall structure floats vertically (upright) in the water. Thereafter, subsequent tank flooding sinks the sea wall structure to the sea bed, where it rests. Yet further flooding of yet further tanks, for example by pumping water into above-sea level tanks can be used to drive the base of the sea wall structure into the sea bed. In relation to the latter, the base (lower edge) of the sea wall structure suitably comprises a pile-like structure, such a downwardly extending legs/pins/skirts that can pile into the sea bed, or a hollow/recess on its lower edge, which can be driven into the sea bed, or evacuated in a “suction pile” fashion to anchor the sea wall structure into the sea bed.

Further sea wall structures can then be installed adjacent to the already-installed sea wall structures, to form a contiguous sea wall. Two or more sea walls so formed may be formed in a generally parallel, spaced-apart relationship, to form a two-walled structure, which can be topped, for example, by a deck/roadway to form a causeway or access. The space between the sea walls can be backfilled, if desired, with various materials, including sand, gravel, building detritus, landfill material etc., or left empty (or emptied) to form a caisson between the sea walls.

It will be appreciated from the foregoing that the invention can be used in the construction of small- and large-scale civil engineering projects, such as tidal barrages for electricity generation, dykes for reclaiming land, tidal/flood/coastal erosion defences, and in tidal energy generation and storage systems, such as that described in UK Patent No: GB2507362.

Embodiments of the invention shall now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a sea wall structure in accordance with the invention;

FIG. 2 is a perspective view of a partial sea wall formed by two adjacent sea wall structures as shown in FIG. 1;

FIG. 3 is a partial front view of the two sea wall structures of FIG. 2 showing how the cups and pins align;

FIG. 4 is a detail view of FIG. 3 showing the engagement of the cups and pins, and an optional steel pile;

FIG. 5 is a schematic plan view on the of FIG. 3 showing how the two sea wall structures mate, when coupled;

FIGS. 6 to 11 are a sequence of plan views showing how a sea wall structure in accordance with the invention can be manufactured;

FIG. 12 is a schematic cross-section of FIG. 11 on XII;

FIG. 12A is a schematic cross-section of a variant of the sea wall structure shown in FIG. 12;

FIG. 13 is a schematic view of a sea wall structure in accordance with the invention;

FIGS. 14 and 15 are schematic side views showing the installation of a sea wall structure in accordance with the invention;

FIG. 16 is a schematic cross-section of a sea wall installed with a supporting buttress;

FIG. 17 is a schematic cross-section of a causeway/caisson formed using two sea walls in accordance with the invention;

FIG. 18 is a schematic cross-section of a causeway/caisson formed with pile-supported sea walls in accordance with the invention; and

FIG. 19 is a perspective view of a tidal power generation and storage system, such as that described in UK Patent No: GB2507362, constructed using sea walls in accordance with the invention.

Referring to FIG. 1 of the drawings, a sea wall structure 10 in accordance with the invention comprises a cast concrete supporting structure 12, which has an array (in this case a 5×9 array) of tanks 14 moulded into it. The sea wall structure 10 is generally cuboidal in shape—having vertical left 16 and right 18 side edges, a horizontal upper edge 20 and a horizontal lower edge 22. Extending downwardly from the lower edge 22 are a set of piles or skirts 24, which can be driven into the seabed to support the sea wall structure 10, as shall be described below.

The left 16 and right 18 side edges of the sea wall structure 10 each have a lip formation 26 intimately formed in the cast concrete supporting structure 12, the function of which shall be described in greater detail below. The left 16 and right 18 side edges of the sea wall structure 10 are also provided with complimentary coupling members, in the form of pins 28 (affixed to the right side edge 18) and cups 30 (connected to the left side edge 16). As can be seen from FIG. 1 of the drawings, the sea wall structure is a modular unit, which can be installed along with other like units to form a sea wall as shown in FIGS. 2, 16, 17 and 18 of the drawings.

Referring now to FIG. 2 of the drawings, a sea wall 100 can be assembled by connecting together a series of like sea wall structures 10 by connecting the pins 28 and cups 30, as previously described, together.

In FIG. 2 of the drawings, the left-hand sea wall structure 10 is installed in the seabed and is therefore slightly lower than the right-hand sea wall structure 10′, which has yet to be driven into the seabed. The right-hand sea wall structure 10′ is offered up to the pre-installed sea wall structure 10 and its pins 28 are offered-up to the cups 30 of the pre-installed sea wall structure 10. Upon driving the right-hand sea wall structure 10′ into the seabed, its pins 28 engage with the cups 30 of the pre-installed sea wall structure 10, to form a modular assembly. The process can, of course, be repeated by adding additional sea wall structures 10 to the sea wall 100, to extend the width of the sea wall 100 laterally, as required.

The engagement of the pins 28 and cups 30 is shown in greater detail in FIGS. 3 to 5 of the drawings. Again, the left-hand sea wall structure 10 is pre-installed, that is to say with its piles 24 driven fully into the seabed (not shown) to anchor the sea wall structure 10 in position.

The next sea wall structure 10′ is then moved into position with its pins 28 located above the cups 30 of the pre-installed sea wall structure 10. Next, the (right-hand) sea wall structure 10′ can be sunk into position, whereupon the pins 28, which have chamfered lower peripheral edges, engage with a part-conical portion 32 of the cups 30 of the pre-installed sea wall structure.

As shown in greater detail in FIG. 4 of the drawings, when the right-hand sea wall structure 10′ is driven fully into the seabed (not shown) the pins 28 of the right-hand sea wall structure 10′ are guided into engagement with the cups 30 of the pre-installed sea wall structure 10 by virtue of the part conical guiding formation 32 of the cups 30. Therefore, the additional sea wall structure 10′ is effectively pulled into engagement with the pre-installed sea wall structure 10 by the self-aligning nature of the pins 28 and cups. Finally, and optional steel pile 37 can be inserted through the cups 30 and tubular pins 28, and held in position by driving its lower end into the sea bed and/or using a fastener connecting the pile 37 to the sea wall structure 10.

As can be seen from FIG. 5 of the drawings, which is a schematic plan view on the of FIG. 3, when the right-hand sea wall structure 10′ is connected to the pre-installed sea wall structure 10, the lips 26 of each of the sea wall structures 10, 10′ comes into engagement with the respective opposite side edge 16, 18 of the adjacent sea wall structure 10. A bead of sealant 34 can be used to form a watertight seal between the lips 26 and their corresponding mating side edges 16, 18 of the sea wall structures 10 and/or a grout or sealant 36 can be injected into the cavity formed between the adjacent sea wall structures 10 to further inhibit and/or prevent the leakage of seawater from one side of the sea wall 100 to the other.

FIGS. 6 to 11 are a sequence of drawings showing how the sea wall structure 10 can be manufactured relatively easily, and preferably close to the final installation site of the sea wall 100. FIGS. 6 to 11 are plan views showing how the sea wall structure 10 can be fabricated in a generally horizontal (laid-flat) orientation.

Referring to FIG. 6 of the drawings, a shuttering arrangement 200 is formed by arranging (for example in a jig) a set of side shutters 202, a lower 204 and an upper 206 shutter. A set of generally cuboid blanks 208 are placed inside the shuttering 200 atop the lower shutter 204 to form a mould for the piles 24 as shall become apparent later. The side shutters 202 eventually form the left and right side edges of the sea wall structure 10, and so are made up of formed steel or reinforced concrete members having an integrally-formed lip (not shown) and cups 30 and pins 28 (as described above).

Referring now to FIG. 7 of the drawings, the next step in the procedure is to install a set of reinforcing bars (“rebar”) for concrete, which will later be poured into the shuttering 200. The rebar comprises a peripheral frame 210, a set of vertical rebars 212 (which extend into the pile parts of the structure between the blanks 208) and a set of horizontal rebars 214, which are laid into the shuttering 200 to form a grid-like structure. The lengths of the vertical 212 and horizontal 214 rebars are fabricated in sections which are connected by overlapping the main reinforcement in accordance with the specific reinforced concrete codes. The vertical 212 and horizontal 214 rebars also engage with the inner sidewalls of the shuttering 200, thereby partially self-aligning them in the mould. The alignment of the peripheral frame 210 is accomplished as shall be explained next.

Referring now to FIG. 8 of the drawings, a set of blow-moulded, hollow plastics tanks 14 is placed into the shuttering 200 in a grid-like array.

Each tank 14 has a peripheral flange portion 218, which keys the tank 14 into the concrete, which is poured into the shuttering 200 later. The flanges 218 may also have a set of through holes 202 to further key the tanks 14 into the later-poured concrete.

As can be seen, each tank has extending outwardly from its side edges, a set of connectors 222, which are shown in cross-section in FIG. 8a . Each of the connectors 222 has a supporting limb portion 224, which is integrally formed with the flange 218 or side of each tank 14; and a cup-like formation 226, which clips onto the rebar 210, 212, 214. It will be appreciated that by connecting the tanks 14 to the rebar 210, 212, 214 thus, the spacing and arrangement of the rebar and tanks becomes fixed and is also centred/located within the shuttering 200 by virtue of the lengths of the rebar being configured to engage with the inner sidewalls of the shuttering 200 as well.

As can be seen from FIG. 9 of the drawings, each tank 14 comprises a valve 228, which enables the tanks 14 to be filled with either air or sea water, as required.

Each of the valves 228 is connected to a pipe 230, which is fed around inside the shuttering 200 and which emerges 232 at the top of the shuttering 200.

In use, it is thus possible to fill or empty the tanks 14, as required, by pumping air/water into/out of the tanks 14 via the pipes 230, via an air/water supply connected to the free end 232 of the pipes.

It will also be noted from FIG. 9 that the valves 228 of the tanks 14 are connected in groups thus enabling individual tanks 14, or groups of tanks 14, to be filled/emptied individually, in groups, all in unison.

Turning now to FIG. 10 of the drawings, concrete 234 is poured into the shuttering 200 to a level such that the rebar 210, 212, 214 and the pipework 230, is encased in the concrete 234, but where the tanks 14 slightly protrude above the level of the concrete 234. Notably, the tanks 14, and in particular their corners and/or edges, have rounded or curved profiles, which when encased in concrete, avoids the formation of sharp corners in the concrete, which could serve as stress concentration points in the final structure. Thus, the curvature of the tanks 14 removes stress concentration points, thereby potentially extending the duty cycle of the sea wall structure 10 by reducing the likelihood of the structure developing fatigue stress-induced cracks at the corners of the concrete where it meets the tanks.

Once the concrete 234 has set, it is then possible to remove the shuttering 204 and 206 and thus the sea wall structure 10 is formed.

FIG. 12 is a schematic cross-section of FIG. 11 on XII showing how the tanks 14 and rebar 212 are encased in the concrete 234 to form an integral structure. The sea wall structure can also be fabricated horizontally so that it can be easily launched in readiness for towing to the installation site. Consequently, there are two options for setting out the tanks and steel reinforcement prior to pouring concrete. FIG. 12A shows the tanks 14 located on the base of the seawall structure 10, whereas FIG. 12 shows the tanks 14 located on the top of the sea wall structure 10. The key difference between these two options is that the option shown in FIG. 12A can be completed by a single concrete pour, provided the tanks 14 are fixed or ballasted. On the other hand, the option shown in FIG. 12 may require two pours (if the concrete cannot flow around and under the tanks 14 to form the continuous layer/surface shown at the bottom of FIG. 12): with the tanks 14 having to be located after the first pour (forming a skin or continuous layer/surface) and then held in place during the second pour. Consequently, the option shown in FIG. 12A should be able to be completed quicker, and more cheaply, than the option shown in FIG. 12.

FIG. 13 is a schematic view, similar to that shown in FIG. 9 of the drawings, of the sea wall structure 10 depicted in FIGS. 1 and 2. Identical reference signs have been used to denote identical features to avoid repetition, but it will be noted from FIG. 13 that the arrangement of rebar within the structure is typically more complicated than that described schematically/conceptually above.

FIG. 14 shows how, when the tanks 14 are empty, the sea wall structure 10 can be floated on a body of water 300 and towed, for example using a tug 302 to an intended installation site.

Once brought into position, as shown in FIG. 15 of the drawings, the tanks 14 can be flooded by opening their respective valves 228 in a desired sequence. In this particular example, the lowermost tanks are flooded first; followed by subsequent rows of tanks, which causes the sea wall structure 10 to rotate towards the vertical position as shown by dashed lines in FIG. 15.

The sea wall structure 10 can effectively float in a vertical orientation and thus be manoeuvred precisely into position before subsequent flooding of further tanks, which causes the sea wall structure 10 to sink to the seabed 306. Then, by pumping further water into further tanks (i.e. tanks located above sea level 308, a head of water within the sea wall structure 10 can self-pile it into the seabed 306, thereby driving its piles 24 (or skirts) into the seabed 306 to stabilise it.

This is shown in FIGS. 16, 17 and 18 of the drawings in which the piles and skirts 24 of the sea wall structure 10 have been driven into the seabed 306 to form an initial anchorage.

In FIG. 16 of the drawings, an additional pile or concrete block 308 is placed on/in the seabed 306 behind the sea wall 10/100 and is connected to the sea wall 10/100 by a buttress framework 310. In this way, the sea wall 10/100 is able to hold back a body of water or, as shown in FIG. 16 of the drawings, to support a differential sea level 308, 308′ on opposite sides of the sea wall 10/100.

An alternative arrangement is shown in FIG. 17 of the drawings, in which two opposing sea walls 10/100 are installed side-by-side in a spaced-apart configuration. The sea walls 10/100 can be cross-braced by a supporting framework 312, which serves to stabilise the sea walls 10/100 and form a more rigid structure. The structure can also be topped by a deck 314, which can be used for various purposes, such as a roadway or access along the top of the sea wall 10/100.

A further possibility is shown in FIG. 18 of the drawings in which, again, a pair of spaced-apart sea walls 10/100 are supported by piles 316, which are braced to their respective sea walls 10/100 by a supporting framework 318. Again, this structure can be topped with a deck 314.

With regard to the embodiments shown in FIGS. 17 and 18 of the drawings, the space 320 between the sea walls 100 can either be left empty (i.e. as a caisson), or it can be backfilled with sand or other material, or allowed to flood—depending on the requirements of the application.

Finally, turning now to FIG. 19 of the drawings, a perspective view from above of a tidal power storage and generation system, such as that described in published patent number GB2507362, which is formed by a circular, outer sea wall 100′ which defines a lagoon. The lagoon is divided into three internal lagoons 400, which are separated by three internal sea walls 100″. The outer sea wall 100′ has sluice gates in it to allow seawater 300 into and out of the lagoons at high and low tide; and a set of tidal generators are provided in the internal sea walls 100″ thus enabling power to be generated by allowing seawater to flow between the internal lagoons 400 in the manner described in published patent number GB2507362.

The following statements are not the claims but relate to various features or embodiments of the invention:

-   Statement 1 A sea wall structure comprising a rigid supporting     structure and one or more hollow tanks affixed to the supporting     structure. -   Statement 2 The sea wall structure of statement 1, wherein the     volume of the tank or tanks is such that, when filled with air,     their displacement is sufficient to support the weight of the sea     wall structure and thus enable the sea wall structure to be floated     on water. -   Statement 3 The sea wall structure of any preceding statement,     wherein the tank or tanks, and in particular their corners and/or     edges, are rounded or curved. -   Statement 4 The sea wall structure of any of any preceding     statement, wherein the or each tank comprise one or more engagement     means adapted in use, to engage with rebar of the reinforced     concrete supporting framework.

The invention is not restricted to the details of the foregoing embodiments, which are merely exemplary of the invention. In particular, any shapes, dimensions, materials or properties, whether express or implied are illustrative only, and are not restrictive of the scope of the invention. 

1. A sea wall structure comprising a rigid supporting structure and one or more hollow tanks affixed to the supporting structure, wherein the volume of the tank or tanks is such that, when filled with air, their displacement is sufficient to support the weight of the sea wall structure and thus enable the sea wall structure to be floated on water.
 2. The sea wall structure of claim 1, wherein the supporting framework is manufactured from concrete.
 3. The sea wall structure of claim 2, wherein the supporting framework is manufactured from moulded, reinforced concrete.
 4. The sea wall structure of any preceding claim, wherein the tank or tanks are formed from blow-moulded plastics.
 5. The sea wall structure of any preceding claim, wherein the tank or tanks, are rounded or curved.
 6. The sea wall structure of any preceding claim, wherein the tank's or tanks' corners and/or edges are rounded or curved.
 7. The sea wall structure of any of claims 3 to 6, wherein the or each tank comprises keying formations adapted to key/anchor, and hence affix, the tank or tanks into the concrete.
 8. The sea wall structure of claim 3, wherein the or each tank comprises one or more engagement means adapted in use, to engage with a reinforcing bar of the reinforced concrete of the supporting framework.
 9. The sea wall structure of any of claims 3 to 8, further comprising a bonding or sealing agent interposed between the or each tank and the concrete adapted to improve the adhesion of the concrete to the or each tank.
 10. The sea wall structure of any preceding claim, wherein the side edges of the sea wall structure comprise lips that partially overlap one another when two like sea wall structures are placed side by side.
 11. The sea wall structure of any preceding claim, wherein a lower edge of the sea wall structure comprises one or more piles.
 12. The sea wall structure of any preceding claim, wherein opposite side edges of the sea wall structure comprise complementary connectors to engage adjacent sea wall structures with one another.
 13. The sea wall structure of claim 12, wherein the connectors comprise one or more cups affixed to one side edge of the sea wall structure; and a corresponding number of pins affixed to the opposite side edge of the sea wall structure.
 14. The sea wall structure of claim 13, wherein the connectors are self-centring.
 15. The sea wall structure of claim 14, wherein the or each pin comprises a tapered or chamfered lower end, which engages a part-conical upper portion of the respective cup.
 16. The sea wall structure of any of claims 12 to 15, wherein the connectors are canted such that when they are engaged with one another, at least one of two so connected sea wall structures is pulled into engagement with the other.
 17. The sea wall structure of any preceding claim, wherein the or each tank comprises a valve comprising an outlet communicating with the interior of the tank, and an inlet connected to a fluid source.
 18. The sea wall structure of claim 17, wherein the fluid source comprises sea water in or upon which the sea wall structure is located.
 19. The sea wall structure of claim 17, wherein the fluid source is a fluid supply connected to the valve via pipework.
 20. The sea wall structure of claim 19, wherein the fluid supply comprises any one or more the group comprising: an air supply; a gas supply; a liquid supply; a water supply; a flowable, fluid-like ballast; fine, dry sand; glass beads; and metal powder.
 21. The sea wall structure of any of claims 17 to 20, wherein the valves are controllable remotely to enable each tank to be filled individually, in groups, or together.
 22. A sea wall formed from a plurality of sealingly interconnected sea wall structures according to any preceding claim.
 23. The sea wall of claim 22, further comprising a supporting buttress.
 24. The sea wall of claim 23, wherein the supporting buttress comprises an anchorage spaced apart from the sea wall on the sea bed, and a buttress framework rigidly connecting the sea wall to the anchorage.
 25. The sea wall of claim 22, comprising a pair of generally parallel, spaced-apart sea walls.
 26. The sea wall of claim 25, further comprising any one or more of the group comprising: a deck; cross-bracing between the spaced-apart sea walls; and a pile supporting one of the sea walls.
 27. The sea wall of any of claims 22 to 26 forming part of any one or more of the group comprising: a tidal barrage; a tidal barrage for tidal electricity generation; a dykes; a tidal defence wall; a flood defence wall; a coastal erosion defence wall; and a three-tank tidal energy generation and storage systems (such as that described in UK Patent No: GB2507362).
 28. A method of assembling the sea wall of any of claims 22 to 27 comprising the steps of: floating a first sea wall structure to a desired installation site; flooding the tank or tanks with sea water to cause the sea wall structure to float upright; further flooding the or each tank to a level above sea level to drive a base of the sea wall structure into a sea bed.
 29. The method of claim 28, further comprising repeating the procedure with a second sea wall structure, and engaging a side edge of the second sea wall structure with a side edge of the first sea wall structure.
 30. The method of claim 28 or claim 29, further comprising the steps of: installing an anchorage on the sea bed at a spaced-apart location from the sea wall on the sea bed; and installing a rigid buttress framework between the sea wall and the anchorage.
 31. The method of claims 28 to 30, further comprising forming a pair of generally parallel, spaced-apart sea walls.
 32. The method of claim 31, further comprising any one or more of the steps comprising: installing a deck; installing cross-bracing between the spaced-apart sea walls; installing a pile for supporting one of the sea walls; and backfilling the space between the sea walls.
 33. A method of manufacturing a sea wall structure comprising a rigid supporting structure and one or more hollow tanks affixed to the supporting structure, the method comprising the steps of: forming a mould; placing a grid-like array of reinforcing bars into the mould; installing a set hollow tanks into the mould and connecting the tanks to the reinforcing bars; pouring concrete into the mould into the interconnected spaces between the tanks to form the supporting structure; allowing the concrete to set render the supporting structure rigid; and removing the sea wall structure from the mould.
 34. The method of claim 33, wherein the step of connecting the tanks to the reinforcing bars is accomplished by engaging connectors of the tanks with the reinforcing bars.
 35. The method of claim 33 or 34, further comprising the step of installing flooding/emptying pipework for the tanks.
 36. The method of any or claims 33 to 35, wherein the step of pouring concrete into the mould comprises filling the mould with concrete to a level whereby the reinforcing bars are encased in the concrete, but whereby the tanks slightly protrude above the level of the concrete.
 37. A sea wall structure substantially as hereinbefore described, with reference to, and as illustrated in, FIGS. 1 and 3 to 13 of the accompanying drawings.
 38. A sea wall substantially as hereinbefore described, with reference to, and as illustrated in, FIGS. 2 and 16 to 19 of the accompanying drawings.
 39. A method of manufacturing a sea wall structure substantially as herein before described, with reference to, and as illustrated in, FIGS. 6 to 11 of the accompanying drawings. 